diff --git a/src/common/utils/constructeur-link.util.ts b/src/common/utils/constructeur-link.util.ts
new file mode 100644
index 0000000..7ca8f26
--- /dev/null
+++ b/src/common/utils/constructeur-link.util.ts
@@ -0,0 +1,248 @@
+import { Prisma } from '@prisma/client';
+import type { PrismaService } from '../../prisma/prisma.service';
+
+type PrismaExecutor = Prisma.TransactionClient | PrismaService;
+
+type LinkOrientation = {
+  parentColumn: 'A' | 'B';
+  constructeurColumn: 'A' | 'B';
+};
+
+const DEFAULT_ORIENTATIONS: Record<string, LinkOrientation> = {
+  _MachineConstructeurs: { parentColumn: 'A', constructeurColumn: 'B' },
+  _ComposantConstructeurs: { parentColumn: 'A', constructeurColumn: 'B' },
+  _PieceConstructeurs: { parentColumn: 'A', constructeurColumn: 'B' },
+};
+
+const sanitizeTableName = (tableName: string): string => {
+  if (!/^_[A-Za-z0-9]+$/.test(tableName)) {
+    throw new Error(`Invalid constructeur link table name: ${tableName}`);
+  }
+  return `"${tableName}"`;
+};
+
+const ORIENTATION_CACHE = new Map<string, LinkOrientation>();
+const KNOWN_PARENT_TABLES = new Set(['machines', 'composants', 'pieces']);
+const oppositeColumn = (column: 'A' | 'B'): 'A' | 'B' =>
+  column === 'A' ? 'B' : 'A';
+
+async function resolveOrientation(
+  prisma: PrismaExecutor & {
+    __getConstructeurLinkOrientation?: (
+      table: string,
+    ) => LinkOrientation | Promise<LinkOrientation>;
+  },
+  tableName: string,
+): Promise<LinkOrientation> {
+  const cached = ORIENTATION_CACHE.get(tableName);
+  if (cached) {
+    return cached;
+  }
+
+	  if (typeof prisma.__getConstructeurLinkOrientation === 'function') {
+	    const orientation = await prisma.__getConstructeurLinkOrientation(tableName);
+	    ORIENTATION_CACHE.set(tableName, orientation);
+	    return orientation;
+	  }
+
+  const rows = await prisma.$queryRaw<
+    Array<{ column_name: string; foreign_table_name: string }>
+  >(Prisma.sql`
+    SELECT
+      kcu.column_name,
+      ccu.table_name AS foreign_table_name
+    FROM information_schema.table_constraints tc
+    JOIN information_schema.key_column_usage kcu
+      ON tc.constraint_name = kcu.constraint_name
+      AND tc.table_schema = kcu.table_schema
+    JOIN information_schema.constraint_column_usage ccu
+      ON tc.constraint_name = ccu.constraint_name
+      AND tc.table_schema = ccu.table_schema
+    WHERE tc.constraint_type = 'FOREIGN KEY'
+      AND tc.table_schema = 'public'
+      AND tc.table_name = ${tableName}
+  `);
+
+  let parentColumn: 'A' | 'B' | null = null;
+  let constructeurColumn: 'A' | 'B' | null = null;
+
+  for (const row of rows) {
+    const column = row.column_name?.toUpperCase?.() as 'A' | 'B' | undefined;
+    if (column !== 'A' && column !== 'B') {
+      continue;
+    }
+
+    if (row.foreign_table_name === 'constructeurs') {
+      constructeurColumn = column;
+      continue;
+    }
+
+    if (KNOWN_PARENT_TABLES.has(row.foreign_table_name)) {
+      parentColumn = column;
+      continue;
+    }
+
+    if (!parentColumn) {
+      parentColumn = column;
+    }
+  }
+
+  if (parentColumn && !constructeurColumn) {
+    constructeurColumn = oppositeColumn(parentColumn);
+  } else if (!parentColumn && constructeurColumn) {
+    parentColumn = oppositeColumn(constructeurColumn);
+  }
+
+  if (!parentColumn || !constructeurColumn) {
+    const fallback = DEFAULT_ORIENTATIONS[tableName];
+    if (fallback) {
+      parentColumn ??= fallback.parentColumn;
+      constructeurColumn ??= fallback.constructeurColumn;
+    }
+  }
+
+  if (!parentColumn || !constructeurColumn) {
+    const columns = rows
+      .map(
+        (row) =>
+          row.column_name?.toUpperCase?.() as 'A' | 'B' | undefined,
+      )
+      .filter((column): column is 'A' | 'B' => column === 'A' || column === 'B');
+
+    if (columns.length === 2) {
+      if (!parentColumn) {
+        parentColumn = columns[0];
+      }
+      if (!constructeurColumn) {
+        const alternative = columns.find((column) => column !== parentColumn);
+        if (alternative) {
+          constructeurColumn = alternative;
+        }
+      }
+    }
+  }
+
+  if (!parentColumn || !constructeurColumn) {
+    throw new Error(
+      `Impossible de déterminer l'orientation de la table ${tableName}.`,
+    );
+  }
+
+  const orientation: LinkOrientation = {
+    parentColumn,
+    constructeurColumn,
+  };
+  ORIENTATION_CACHE.set(tableName, orientation);
+  return orientation;
+}
+
+export async function syncConstructeurLinks(
+  prisma: PrismaExecutor,
+  tableName: string,
+  parentId: string,
+  constructeurIds: string[],
+): Promise<string[]> {
+  const executor = prisma as PrismaExecutor & {
+    __syncConstructeurLinks?: (
+      table: string,
+      parent: string,
+      ids: string[],
+    ) => Promise<void> | void;
+    __getConstructeurLinkOrientation?: (
+      table: string,
+    ) => LinkOrientation | Promise<LinkOrientation>;
+  };
+
+  const table = Prisma.raw(sanitizeTableName(tableName));
+  const uniqueConstructeurIds = Array.from(
+    new Set(
+      constructeurIds
+        .map((value) => (typeof value === 'string' ? value.trim() : ''))
+        .filter((value) => value.length > 0),
+    ),
+  );
+  let targetConstructeurIds = uniqueConstructeurIds;
+
+  const constructeurDelegate = (executor as any)?.constructeur as
+    | {
+        findMany?: (args: {
+          where: { id: { in: string[] } };
+          select: { id: boolean };
+        }) => Promise<Array<{ id: string }>>;
+      }
+    | undefined;
+
+  if (targetConstructeurIds.length > 0 && constructeurDelegate?.findMany) {
+    const existing = await constructeurDelegate.findMany({
+      where: { id: { in: targetConstructeurIds } },
+      select: { id: true },
+    });
+    const existingIds = new Set(existing.map(({ id }) => id));
+    targetConstructeurIds = targetConstructeurIds.filter((id) =>
+      existingIds.has(id),
+    );
+  }
+
+  const orientation = await resolveOrientation(executor, tableName);
+
+  if (typeof executor.__syncConstructeurLinks === 'function') {
+    await executor.__syncConstructeurLinks(
+      tableName,
+      parentId,
+      targetConstructeurIds,
+    );
+    return targetConstructeurIds;
+  }
+
+  await prisma.$executeRaw(
+    Prisma.sql`DELETE FROM ${table} WHERE ${Prisma.raw(
+      `"${orientation.parentColumn}"`,
+    )} = ${parentId}`,
+  );
+
+  if (targetConstructeurIds.length === 0) {
+    return [];
+  }
+
+  const valueTuples = targetConstructeurIds.map((constructeurId) =>
+    Prisma.sql`(${parentId}, ${constructeurId})`,
+  );
+
+  await prisma.$executeRaw(
+    Prisma.sql`
+      INSERT INTO ${table} (
+        ${Prisma.raw(`"${orientation.parentColumn}"`)},
+        ${Prisma.raw(`"${orientation.constructeurColumn}"`)}
+      )
+      VALUES ${Prisma.join(valueTuples)}
+      ON CONFLICT DO NOTHING
+    `,
+  );
+  return fetchConstructeurIds(executor, tableName, parentId, orientation);
+}
+
+export async function fetchConstructeurIds(
+  prisma: PrismaExecutor,
+  tableName: string,
+  parentId: string,
+  orientationOverride?: LinkOrientation,
+): Promise<string[]> {
+  const orientation =
+    orientationOverride ?? (await resolveOrientation(prisma as any, tableName));
+  const table = Prisma.raw(sanitizeTableName(tableName));
+  const rows = await prisma.$queryRaw<Array<{ constructeurId: string | null }>>(
+    Prisma.sql`
+      SELECT ${Prisma.raw(
+        `"${orientation.constructeurColumn}"`,
+      )} AS "constructeurId"
+      FROM ${table}
+      WHERE ${Prisma.raw(`"${orientation.parentColumn}"`)} = ${parentId}
+    `,
+  );
+
+  return rows
+    .map((row) =>
+      typeof row.constructeurId === 'string' ? row.constructeurId : null,
+    )
+    .filter((id): id is string => Boolean(id));
+}
diff --git a/src/composants/composants.service.ts b/src/composants/composants.service.ts
index faf8f01..d55d407 100644
--- a/src/composants/composants.service.ts
+++ b/src/composants/composants.service.ts
@@ -9,6 +9,7 @@ import {
   COMPONENT_WITH_RELATIONS_INCLUDE,
   ComposantWithRelations,
 } from '../common/constants/component-includes';
+import { syncConstructeurLinks } from '../common/utils/constructeur-link.util';
 
 @Injectable()
 export class ComposantsService {
@@ -16,7 +17,10 @@ export class ComposantsService {
 
   private async buildCreateInput(
     createComposantDto: CreateComposantDto,
-  ): Promise<Prisma.ComposantCreateInput> {
+  ): Promise<{
+    data: Prisma.ComposantCreateInput;
+    constructeurIds: string[];
+  }> {
     const data: Prisma.ComposantCreateInput = {
       name: createComposantDto.name,
       reference: createComposantDto.reference ?? null,
@@ -29,11 +33,6 @@ export class ComposantsService {
     );
     const resolvedConstructeurIds =
       await this.resolveExistingConstructeurIds(constructeurIds);
-    if (resolvedConstructeurIds.length) {
-      data.constructeurs = {
-        connect: resolvedConstructeurIds.map((id) => ({ id })),
-      };
-    }
 
     if (createComposantDto.typeComposantId) {
       data.typeComposant = {
@@ -45,17 +44,41 @@ export class ComposantsService {
       data.structure = createComposantDto.structure as Prisma.InputJsonValue;
     }
 
-    return data;
+    return { data, constructeurIds: resolvedConstructeurIds };
   }
 
   async create(createComposantDto: CreateComposantDto) {
     try {
+      const { data, constructeurIds } = await this.buildCreateInput(
+        createComposantDto,
+      );
       const created = await this.prisma.composant.create({
-        data: await this.buildCreateInput(createComposantDto),
+        data,
         include: COMPONENT_WITH_RELATIONS_INCLUDE,
       });
 
-      return created as ComposantWithRelations;
+      let syncedConstructeurIds: string[] = [];
+      if (constructeurIds.length > 0) {
+        syncedConstructeurIds = await syncConstructeurLinks(
+          this.prisma,
+          '_ComposantConstructeurs',
+          created.id,
+          constructeurIds,
+        );
+      }
+
+      const refreshed = (await this.prisma.composant.findUnique({
+        where: { id: created.id },
+        include: COMPONENT_WITH_RELATIONS_INCLUDE,
+      })) as ComposantWithRelations | null;
+
+      if (refreshed && syncedConstructeurIds.length > 0) {
+        (refreshed as ComposantWithRelations & {
+          constructeurIds?: string[];
+        }).constructeurIds = [...syncedConstructeurIds];
+      }
+
+      return refreshed;
     } catch (error) {
       this.handlePrismaError(error);
     }
@@ -90,15 +113,14 @@ export class ComposantsService {
       data.prix = updateComposantDto.prix;
     }
 
+    let resolvedConstructeurIds: string[] | undefined;
     if (updateComposantDto.constructeurIds !== undefined) {
       const constructeurIds = this.normalizeConstructeurIds(
         updateComposantDto.constructeurIds,
       );
-      const resolvedConstructeurIds =
-        await this.resolveExistingConstructeurIds(constructeurIds);
-      data.constructeurs = {
-        set: resolvedConstructeurIds.map((id) => ({ id })),
-      };
+      resolvedConstructeurIds = await this.resolveExistingConstructeurIds(
+        constructeurIds,
+      );
     }
 
     if (updateComposantDto.typeComposantId !== undefined) {
@@ -111,12 +133,36 @@ export class ComposantsService {
       data.structure = updateComposantDto.structure as Prisma.InputJsonValue;
     }
 
+    let syncedConstructeurIds: string[] | undefined;
     try {
-      return (await this.prisma.composant.update({
+      await this.prisma.$transaction(async (tx) => {
+        await tx.composant.update({
+          where: { id },
+          data,
+        });
+
+        if (resolvedConstructeurIds !== undefined) {
+          syncedConstructeurIds = await syncConstructeurLinks(
+            tx,
+            '_ComposantConstructeurs',
+            id,
+            resolvedConstructeurIds,
+          );
+        }
+      });
+
+      const refreshed = (await this.prisma.composant.findUnique({
         where: { id },
-        data,
         include: COMPONENT_WITH_RELATIONS_INCLUDE,
-      })) as ComposantWithRelations;
+      })) as ComposantWithRelations | null;
+
+      if (refreshed && syncedConstructeurIds) {
+        (refreshed as ComposantWithRelations & {
+          constructeurIds?: string[];
+        }).constructeurIds = [...syncedConstructeurIds];
+      }
+
+      return refreshed;
     } catch (error) {
       this.handlePrismaError(error);
     }
diff --git a/src/machines/machines.service.ts b/src/machines/machines.service.ts
index 5044bc1..c157afa 100644
--- a/src/machines/machines.service.ts
+++ b/src/machines/machines.service.ts
@@ -10,6 +10,10 @@ import {
   MachinePieceLinkInput,
 } from '../shared/dto/machine.dto';
 import { buildComponentHierarchy } from '../common/utils/component-tree.util';
+import {
+  fetchConstructeurIds,
+  syncConstructeurLinks,
+} from '../common/utils/constructeur-link.util';
 
 const CUSTOM_FIELD_SELECT = {
   id: true,
@@ -402,12 +406,18 @@ export class MachinesService {
     | (MachineWithRelations & {
         componentLinks: HydratedComponentLink[];
         pieceLinks: HydratedPieceLink[];
+        constructeurIds: string[];
+        constructeurs: MachineWithRelations['constructeurs'];
       })
     | null {
     if (!machine) {
       return machine;
     }
 
+    const resolvedConstructeurs = Array.isArray(machine.constructeurs)
+      ? machine.constructeurs
+      : [];
+
     const componentLinks = this.hydrateComponentLinks(
       machine.componentLinks ?? [],
     );
@@ -419,10 +429,18 @@ export class MachinesService {
     const hydratedMachine = machine as MachineWithRelations & {
       componentLinks: HydratedComponentLink[];
       pieceLinks: HydratedPieceLink[];
+      constructeurIds: string[];
+      constructeurs: MachineWithRelations['constructeurs'];
     };
 
     hydratedMachine.componentLinks = componentLinks;
     hydratedMachine.pieceLinks = rootPieceLinks;
+    hydratedMachine.constructeurIds = resolvedConstructeurs
+      .map((constructeur) =>
+        typeof constructeur?.id === 'string' ? constructeur.id : null,
+      )
+      .filter((id): id is string => Boolean(id));
+    hydratedMachine.constructeurs = resolvedConstructeurs;
 
     return hydratedMachine;
   }
@@ -432,10 +450,85 @@ export class MachinesService {
   ): (MachineWithRelations & {
     componentLinks: HydratedComponentLink[];
     pieceLinks: HydratedPieceLink[];
+    constructeurIds: string[];
+    constructeurs: MachineWithRelations['constructeurs'];
   })[] {
     return machines.map((machine) => this.hydrateMachine(machine)!);
   }
 
+  private async ensureMachineConstructeurs<
+    T extends
+      | (MachineWithRelations & {
+          componentLinks: HydratedComponentLink[];
+          pieceLinks: HydratedPieceLink[];
+          constructeurIds: string[];
+          constructeurs: MachineWithRelations['constructeurs'];
+        })
+      | null,
+  >(machine: T): Promise<T> {
+    if (!machine) {
+      return machine;
+    }
+
+    const existingConstructeurs = Array.isArray(machine.constructeurs)
+      ? machine.constructeurs
+      : [];
+
+    const idsFromConstructeurs = existingConstructeurs
+      .map((constructeur) =>
+        typeof constructeur?.id === 'string' ? constructeur.id : null,
+      )
+      .filter((id): id is string => Boolean(id));
+
+    const initialIds =
+      Array.isArray(machine.constructeurIds) && machine.constructeurIds.length > 0
+        ? machine.constructeurIds
+        : idsFromConstructeurs;
+
+    let resolvedIds = initialIds;
+    if (resolvedIds.length === 0) {
+      resolvedIds = await fetchConstructeurIds(
+        this.prisma,
+        '_MachineConstructeurs',
+        machine.id,
+      );
+    }
+
+    machine.constructeurIds = [...resolvedIds];
+
+    if (
+      existingConstructeurs.length > 0 &&
+      resolvedIds.length === existingConstructeurs.length
+    ) {
+      return machine;
+    }
+
+    if (resolvedIds.length === 0) {
+      machine.constructeurs = [];
+      return machine;
+    }
+
+    const constructeurs = await this.prisma.constructeur.findMany({
+      where: { id: { in: resolvedIds } },
+    });
+    const byId = new Map(constructeurs.map((item) => [item.id, item]));
+
+    const orderedConstructeurs = resolvedIds
+      .map((id) => byId.get(id))
+      .filter(
+        (
+          record,
+        ): record is (typeof constructeurs)[number] =>
+          Boolean(record),
+      );
+
+    machine.constructeurs =
+      orderedConstructeurs as MachineWithRelations['constructeurs'];
+
+    return machine;
+  }
+
+
   private slugifyName(name: string): string {
     return name
       .normalize('NFD')
@@ -1744,36 +1837,27 @@ export class MachinesService {
     const { componentRequirementMap, pieceRequirementMap } =
       this.buildConfigurationContext(typeMachine, componentLinks, pieceLinks);
 
-    let machine: Awaited<ReturnType<typeof this.prisma.machine.create>>;
-    try {
-      const createData: any = {
-        ...machineData,
-      };
+    const baseMachine = await this.prisma.machine.create({
+      data: machineData,
+      include: {
+        site: true,
+        typeMachine: true,
+        constructeurs: true,
+      },
+    });
 
-      if (resolvedConstructeurIds.length) {
-        createData.constructeurs = {
-          connect: resolvedConstructeurIds.map((id) => ({ id })),
-        };
-      }
-
-      machine = await this.prisma.machine.create({
-        data: createData,
-        include: {
-          site: true,
-          typeMachine: true,
-          constructeurs: true,
-        },
-      });
-    } catch (error) {
-      this.handlePrismaError(error);
-      return;
-    }
+    const syncedConstructeurIds = await syncConstructeurLinks(
+      this.prisma,
+      '_MachineConstructeurs',
+      baseMachine.id,
+      resolvedConstructeurIds,
+    );
 
     try {
       if (typeMachine.customFields && typeMachine.customFields.length > 0) {
         await this.createMachineCustomFieldsFromType(
           this.prisma,
-          machine.id,
+          baseMachine.id,
           typeMachine.customFields,
           typeMachine.id,
         );
@@ -1781,39 +1865,48 @@ export class MachinesService {
 
       const componentIndex = await this.createComponentLinksForMachine(
         this.prisma,
-        machine.id,
+        baseMachine.id,
         componentRequirementMap,
         componentLinks,
       );
 
       await this.createPieceLinksForMachine(
         this.prisma,
-        machine.id,
+        baseMachine.id,
         pieceRequirementMap,
         pieceLinks,
         componentIndex,
       );
     } catch (error) {
       await this.prisma.machine
-        .delete({ where: { id: machine.id } })
+        .delete({ where: { id: baseMachine.id } })
         .catch(() => undefined);
       throw error;
     }
 
     const createdMachine = await this.prisma.machine.findUnique({
-      where: { id: machine.id },
+      where: { id: baseMachine.id },
       include: MACHINE_DEFAULT_INCLUDE,
     });
 
-    return this.hydrateMachine(createdMachine);
+    const hydrated = this.hydrateMachine(createdMachine);
+    if (hydrated && syncedConstructeurIds.length > 0) {
+      hydrated.constructeurIds = [...syncedConstructeurIds];
+    }
+    return this.ensureMachineConstructeurs(hydrated);
   }
 
   async findAll() {
     const machines = await this.prisma.machine.findMany({
       include: MACHINE_DEFAULT_INCLUDE,
     });
-
-    return this.hydrateMachines(machines);
+    const hydrated = this.hydrateMachines(machines);
+    const enriched = await Promise.all(
+      hydrated.map((machine) => this.ensureMachineConstructeurs(machine)),
+    );
+    return enriched.filter(
+      (machine): machine is NonNullable<typeof machine> => Boolean(machine),
+    );
   }
 
   async findOne(id: string) {
@@ -1821,8 +1914,8 @@ export class MachinesService {
       where: { id },
       include: MACHINE_DEFAULT_INCLUDE,
     });
-
-    return this.hydrateMachine(machine);
+    const hydrated = this.hydrateMachine(machine);
+    return this.ensureMachineConstructeurs(hydrated);
   }
 
   async reconfigure(id: string, reconfigureMachineDto: ReconfigureMachineDto) {
@@ -1877,7 +1970,8 @@ export class MachinesService {
       include: MACHINE_DEFAULT_INCLUDE,
     });
 
-    return this.hydrateMachine(updatedMachine);
+    const hydrated = this.hydrateMachine(updatedMachine);
+    return this.ensureMachineConstructeurs(hydrated);
   }
 
   async update(id: string, updateMachineDto: UpdateMachineDto) {
@@ -1894,15 +1988,13 @@ export class MachinesService {
       data.reference = reference;
     }
 
+    let resolvedConstructeurIds: string[] | undefined;
     if (constructeurIds !== undefined) {
       const normalizedConstructeurIds =
         this.normalizeConstructeurIds(constructeurIds);
-      const resolvedConstructeurIds = await this.resolveExistingConstructeurIds(
+      resolvedConstructeurIds = await this.resolveExistingConstructeurIds(
         normalizedConstructeurIds,
       );
-      data.constructeurs = {
-        set: resolvedConstructeurIds.map((id) => ({ id })),
-      };
     }
 
     if (prix !== undefined) {
@@ -1921,14 +2013,34 @@ export class MachinesService {
         : { disconnect: true };
     }
 
+    let syncedConstructeurIds: string[] | undefined;
     try {
-      const machine = await this.prisma.machine.update({
+      await this.prisma.$transaction(async (tx) => {
+        await tx.machine.update({
+          where: { id },
+          data,
+        });
+
+        if (resolvedConstructeurIds !== undefined) {
+          syncedConstructeurIds = await syncConstructeurLinks(
+            tx,
+            '_MachineConstructeurs',
+            id,
+            resolvedConstructeurIds,
+          );
+        }
+      });
+
+      const refreshedMachine = await this.prisma.machine.findUnique({
         where: { id },
-        data,
         include: MACHINE_DEFAULT_INCLUDE,
       });
 
-      return this.hydrateMachine(machine);
+      const hydrated = this.hydrateMachine(refreshedMachine);
+      if (hydrated && syncedConstructeurIds) {
+        hydrated.constructeurIds = [...syncedConstructeurIds];
+      }
+      return this.ensureMachineConstructeurs(hydrated);
     } catch (error) {
       this.handlePrismaError(error);
     }
diff --git a/src/pieces/pieces.service.ts b/src/pieces/pieces.service.ts
index 02e120d..d3ef833 100644
--- a/src/pieces/pieces.service.ts
+++ b/src/pieces/pieces.service.ts
@@ -1,6 +1,7 @@
 import { ConflictException, Injectable } from '@nestjs/common';
 import { Prisma } from '@prisma/client';
 import { PrismaService } from '../prisma/prisma.service';
+import { syncConstructeurLinks } from '../common/utils/constructeur-link.util';
 import { CreatePieceDto, UpdatePieceDto } from '../shared/dto/piece.dto';
 import { PieceModelStructureSchema } from '../shared/schemas/inventory';
 import type { PieceModelStructure } from '../shared/types/inventory';
@@ -35,7 +36,7 @@ export class PiecesService {
 
   private async buildCreateInput(
     createPieceDto: CreatePieceDto,
-  ): Promise<Prisma.PieceCreateInput> {
+  ): Promise<{ data: Prisma.PieceCreateInput; constructeurIds: string[] }> {
     const data: Prisma.PieceCreateInput = {
       name: createPieceDto.name,
       reference: createPieceDto.reference ?? null,
@@ -47,11 +48,6 @@ export class PiecesService {
     );
     const resolvedConstructeurIds =
       await this.resolveExistingConstructeurIds(constructeurIds);
-    if (resolvedConstructeurIds.length) {
-      data.constructeurs = {
-        connect: resolvedConstructeurIds.map((id) => ({ id })),
-      };
-    }
 
     if (createPieceDto.typePieceId) {
       data.typePiece = {
@@ -59,25 +55,46 @@ export class PiecesService {
       };
     }
 
-    return data;
+    return { data, constructeurIds: resolvedConstructeurIds };
   }
 
   async create(createPieceDto: CreatePieceDto) {
     try {
+      const { data, constructeurIds } = await this.buildCreateInput(
+        createPieceDto,
+      );
       const created = await this.prisma.piece.create({
-        data: await this.buildCreateInput(createPieceDto),
+        data,
         include: PIECE_WITH_RELATIONS_INCLUDE,
       });
 
+      let syncedConstructeurIds: string[] = [];
+      if (constructeurIds.length > 0) {
+        syncedConstructeurIds = await syncConstructeurLinks(
+          this.prisma,
+          '_PieceConstructeurs',
+          created.id,
+          constructeurIds,
+        );
+      }
+
       await this.applyPieceSkeleton({
         pieceId: created.id,
         typePiece: created.typePiece as PieceTypeWithSkeleton | null,
+        prisma: this.prisma,
       });
 
-      return this.prisma.piece.findUnique({
+      const refreshed = await this.prisma.piece.findUnique({
         where: { id: created.id },
         include: PIECE_WITH_RELATIONS_INCLUDE,
       });
+
+      if (refreshed && syncedConstructeurIds.length > 0) {
+        (refreshed as typeof refreshed & { constructeurIds?: string[] }).constructeurIds =
+          [...syncedConstructeurIds];
+      }
+
+      return refreshed;
     } catch (error) {
       this.handlePrismaError(error);
     }
@@ -112,15 +129,14 @@ export class PiecesService {
       data.prix = updatePieceDto.prix;
     }
 
+    let resolvedConstructeurIds: string[] | undefined;
     if (updatePieceDto.constructeurIds !== undefined) {
       const constructeurIds = this.normalizeConstructeurIds(
         updatePieceDto.constructeurIds,
       );
-      const resolvedConstructeurIds =
-        await this.resolveExistingConstructeurIds(constructeurIds);
-      data.constructeurs = {
-        set: resolvedConstructeurIds.map((id) => ({ id })),
-      };
+      resolvedConstructeurIds = await this.resolveExistingConstructeurIds(
+        constructeurIds,
+      );
     }
 
     if (updatePieceDto.typePieceId !== undefined) {
@@ -129,22 +145,42 @@ export class PiecesService {
         : { disconnect: true };
     }
 
+    let syncedConstructeurIds: string[] | undefined;
     try {
-      const updated = await this.prisma.piece.update({
+      await this.prisma.$transaction(async (tx) => {
+        const updated = await tx.piece.update({
+          where: { id },
+          data,
+          include: PIECE_WITH_RELATIONS_INCLUDE,
+        });
+
+        if (resolvedConstructeurIds !== undefined) {
+          syncedConstructeurIds = await syncConstructeurLinks(
+            tx,
+            '_PieceConstructeurs',
+            id,
+            resolvedConstructeurIds,
+          );
+        }
+
+        await this.applyPieceSkeleton({
+          pieceId: updated.id,
+          typePiece: updated.typePiece as PieceTypeWithSkeleton | null,
+          prisma: tx,
+        });
+      });
+
+      const refreshed = await this.prisma.piece.findUnique({
         where: { id },
-        data,
         include: PIECE_WITH_RELATIONS_INCLUDE,
       });
 
-      await this.applyPieceSkeleton({
-        pieceId: updated.id,
-        typePiece: updated.typePiece as PieceTypeWithSkeleton | null,
-      });
+      if (refreshed && syncedConstructeurIds) {
+        (refreshed as typeof refreshed & { constructeurIds?: string[] }).constructeurIds =
+          [...syncedConstructeurIds];
+      }
 
-      return this.prisma.piece.findUnique({
-        where: { id: updated.id },
-        include: PIECE_WITH_RELATIONS_INCLUDE,
-      });
+      return refreshed;
     } catch (error) {
       this.handlePrismaError(error);
     }
@@ -211,9 +247,11 @@ export class PiecesService {
   private async applyPieceSkeleton({
     pieceId,
     typePiece,
+    prisma,
   }: {
     pieceId: string;
     typePiece: PieceTypeWithSkeleton | null;
+    prisma: Prisma.TransactionClient | PrismaService;
   }) {
     if (!typePiece?.id) {
       return;
@@ -230,8 +268,13 @@ export class PiecesService {
 
     const customFields = skeleton.customFields ?? [];
 
-    await this.ensurePieceCustomFieldDefinitions(typePiece.id, customFields);
+    await this.ensurePieceCustomFieldDefinitions(
+      prisma,
+      typePiece.id,
+      customFields,
+    );
     await this.createPieceCustomFieldValues(
+      prisma,
       pieceId,
       typePiece.id,
       customFields,
@@ -275,6 +318,7 @@ export class PiecesService {
   }
 
   private async ensurePieceCustomFieldDefinitions(
+    prisma: Prisma.TransactionClient | PrismaService,
     typePieceId: string,
     customFields: PieceModelStructure['customFields'],
   ) {
@@ -286,7 +330,7 @@ export class PiecesService {
       return;
     }
 
-    const existing = await this.prisma.customField.findMany({
+    const existing = await prisma.customField.findMany({
       where: { typePieceId },
       select: { id: true, name: true, orderIndex: true },
     });
@@ -312,7 +356,7 @@ export class PiecesService {
       const existingField = existingByName.get(name);
       if (existingField) {
         if (existingField.orderIndex !== index) {
-          await this.prisma.customField.update({
+          await prisma.customField.update({
             where: { id: existingField.id },
             data: { orderIndex: index },
           });
@@ -324,7 +368,7 @@ export class PiecesService {
       const required = Boolean(field.required);
       const options = this.normalizeOptions(field);
 
-      const created = await this.prisma.customField.create({
+      const created = await prisma.customField.create({
         data: {
           name,
           type,
@@ -341,6 +385,7 @@ export class PiecesService {
   }
 
   private async createPieceCustomFieldValues(
+    prisma: Prisma.TransactionClient | PrismaService,
     pieceId: string,
     typePieceId: string,
     customFields: PieceModelStructure['customFields'],
@@ -353,7 +398,7 @@ export class PiecesService {
       return;
     }
 
-    const definitions = await this.prisma.customField.findMany({
+    const definitions = await prisma.customField.findMany({
       where: { typePieceId },
       select: { id: true, name: true },
     });
@@ -369,7 +414,7 @@ export class PiecesService {
       ]),
     );
 
-    const existingValues = await this.prisma.customFieldValue.findMany({
+    const existingValues = await prisma.customFieldValue.findMany({
       where: { pieceId },
       select: { customFieldId: true },
     });
@@ -393,7 +438,7 @@ export class PiecesService {
         continue;
       }
 
-      await this.prisma.customFieldValue.create({
+      await prisma.customFieldValue.create({
         data: {
           customFieldId: definitionId,
           pieceId,
diff --git a/src/shared/types/constructeur-summary.type.ts b/src/shared/types/constructeur-summary.type.ts
new file mode 100644
index 0000000..10a16a0
--- /dev/null
+++ b/src/shared/types/constructeur-summary.type.ts
@@ -0,0 +1,6 @@
+export type ConstructeurSummary = {
+  id: string;
+  name: string | null;
+  email: string | null;
+  phone: string | null;
+};
diff --git a/test/app.e2e-spec.ts b/test/app.e2e-spec.ts
index 2d1ba4f..847ff8f 100644
--- a/test/app.e2e-spec.ts
+++ b/test/app.e2e-spec.ts
@@ -109,6 +109,15 @@ type PieceRecord = {
   updatedAt: Date;
 };
 
+type ConstructeurRecord = {
+  id: string;
+  name: string;
+  email: Nullable<string>;
+  phone: Nullable<string>;
+  createdAt: Date;
+  updatedAt: Date;
+};
+
 type MachineComponentLinkRecord = {
   id: string;
   machineId: string;
@@ -202,6 +211,15 @@ class InMemoryPrismaService {
   private customFields: CustomFieldRecord[] = [];
   private customFieldValues: CustomFieldValueRecord[] = [];
   private profiles: ProfileRecord[] = [];
+  private constructeurs: ConstructeurRecord[] = [];
+  private readonly constructeurLinkOrientation: Record<
+    string,
+    { parentColumn: 'A' | 'B'; constructeurColumn: 'A' | 'B' }
+  > = {
+    _MachineConstructeurs: { parentColumn: 'A', constructeurColumn: 'B' },
+    _ComposantConstructeurs: { parentColumn: 'A', constructeurColumn: 'B' },
+    _PieceConstructeurs: { parentColumn: 'A', constructeurColumn: 'B' },
+  };
 
   async onModuleInit() {}
   async onModuleDestroy() {}
@@ -229,6 +247,7 @@ class InMemoryPrismaService {
     this.customFields = [];
     this.customFieldValues = [];
     this.profiles = [];
+    this.constructeurs = [];
   }
 
   private readonly modelTypeDelegate = {
@@ -984,6 +1003,120 @@ class InMemoryPrismaService {
     },
   };
 
+  constructeur = {
+    findMany: async ({ where, select, orderBy }: any = {}) => {
+      let records = [...this.constructeurs];
+
+      if (where?.id?.in) {
+        const ids = Array.isArray(where.id.in) ? where.id.in : [];
+        records = records.filter((item) => ids.includes(item.id));
+      }
+
+      if (where?.OR && Array.isArray(where.OR)) {
+        const termCandidate = where.OR.find(
+          (clause: any) => clause?.name?.contains,
+        );
+        const term =
+          termCandidate?.name?.contains ??
+          termCandidate?.email?.contains ??
+          termCandidate?.phone?.contains ??
+          '';
+        const normalized = term.toLowerCase().trim();
+        if (normalized) {
+          records = records.filter((record) => {
+            const nameMatch = record.name.toLowerCase().includes(normalized);
+            const emailMatch =
+              record.email?.toLowerCase().includes(normalized) ?? false;
+            const phoneMatch =
+              record.phone?.toLowerCase().includes(normalized) ?? false;
+            return nameMatch || emailMatch || phoneMatch;
+          });
+        }
+      }
+
+      if (orderBy?.name) {
+        records = [...records].sort((a, b) =>
+          orderBy.name === 'desc'
+            ? b.name.localeCompare(a.name)
+            : a.name.localeCompare(b.name),
+        );
+      }
+
+      return records.map((record) => this.applySelect(record, select));
+    },
+
+    findUnique: async ({ where, select }: any) => {
+      const record = this.constructeurs.find((item) => item.id === where?.id);
+      return record ? this.applySelect(record, select) : null;
+    },
+
+    findFirst: async ({ where, select }: any = {}) => {
+      if (where?.name?.equals) {
+        const target = where.name.equals.toLowerCase();
+        const record = this.constructeurs.find(
+          (item) => item.name.toLowerCase() === target,
+        );
+        return record ? this.applySelect(record, select) : null;
+      }
+      return null;
+    },
+
+    create: async ({ data, select }: any) => {
+      const now = new Date();
+      const record: ConstructeurRecord = {
+        id: data.id ?? generateId('constructeur'),
+        name: data.name?.trim?.() ?? '',
+        email: data.email?.trim?.() ?? null,
+        phone: data.phone?.trim?.() ?? null,
+        createdAt: now,
+        updatedAt: now,
+      };
+      this.constructeurs.push(record);
+      return this.applySelect(record, select);
+    },
+
+    update: async ({ where, data, select }: any) => {
+      const record = this.constructeurs.find((item) => item.id === where?.id);
+      if (!record) {
+        throw new Error('Constructeur not found');
+      }
+      if (data.name !== undefined) {
+        record.name =
+          this.applyUpdateValue<string>(data.name)?.trim?.() ?? record.name;
+      }
+      if (data.email !== undefined) {
+        record.email =
+          this.applyUpdateValue<string | null>(data.email)?.trim?.() ?? null;
+      }
+      if (data.phone !== undefined) {
+        record.phone =
+          this.applyUpdateValue<string | null>(data.phone)?.trim?.() ?? null;
+      }
+      record.updatedAt = new Date();
+      return this.applySelect(record, select);
+    },
+
+    delete: async ({ where, select }: any) => {
+      const index = this.constructeurs.findIndex(
+        (item) => item.id === where?.id,
+      );
+      if (index === -1) {
+        throw new Error('Constructeur not found');
+      }
+      const [deleted] = this.constructeurs.splice(index, 1);
+      return this.applySelect(deleted, select);
+    },
+  };
+
+  async __getConstructeurLinkOrientation(table: string) {
+    return (
+      this.constructeurLinkOrientation[table] ?? {
+        parentColumn: 'A',
+        constructeurColumn: 'B',
+      }
+    );
+  }
+
   profile = {
     count: async ({ where }: any) => {
       return this.profiles.filter((profile) => {
@@ -1315,6 +1448,40 @@ class InMemoryPrismaService {
       .map((item) => ({ ...item }));
   }
 
+  async __syncConstructeurLinks(
+    table: string,
+    parentId: string,
+    ids: string[],
+  ): Promise<void> {
+    const filtered = ids.filter((id) =>
+      this.constructeurs.some((item) => item.id === id),
+    );
+
+    switch (table) {
+      case '_MachineConstructeurs':
+        this.assignConstructeurs(this.machines, parentId, filtered);
+        break;
+      case '_ComposantConstructeurs':
+        this.assignConstructeurs(this.composants, parentId, filtered);
+        break;
+      case '_PieceConstructeurs':
+        this.assignConstructeurs(this.pieces, parentId, filtered);
+        break;
+      default:
+        throw new Error(`Unsupported constructeur link table: ${table}`);
+    }
+  }
+
+  private assignConstructeurs<
+    T extends { id: string; constructeurIds: string[] },
+  >(collection: T[], parentId: string, ids: string[]) {
+    const record = collection.find((item) => item.id === parentId);
+    if (!record) {
+      return;
+    }
+    record.constructeurIds = [...ids];
+  }
+
   private buildMachine(machine: MachineRecord, include: any) {
     const base: any = { ...machine };